Leptons: There are 6 leptons (and their corresponding anti-leptons). One 1st generation lepton is the electron previously discussed. The electron has a mass of GeV/c^2. The 2nd generation equivalent, the muon was discovered in cosmic rays in 1937 and has a mass of GeV/c^2. The tau is in the 3rd generation, was found in 1975 at SLAC from electron-position annihilation and has a mass of GeV/c^2. There are 3 neutrinos, one for each generation. They were originally thought up as bookkeeping devices to account for the lost energy and momentum in &beta -decay. Their existence has since been verified. Lepton Number is a conserved quantity, meaning that in reactions the number of leptons initially balances those finally. In this scheme, leptons are given a lepton number of 1 while their antiparticles have lepton number -1.

Quarks: Quarks were discovered by a method very similar to Rutherford's Scattering Experiment called Deep Inelastic Scattering. In this experiment, high energy electrons are scattered off protons. From the results of this experiment, the proton was found to have substructure. The proton is made up of the combination uud. These are the two first generation quarks. The up (u) quark has charge +2/3 and mass GeV/c^2 while the down (d) quark has charge -1/3 and mass GeV/c^2. The strange (s) quark was created along with the quark model, has mass 0.1 GeV/c^2 and charge identical to the down quark. Rounding out the 2nd generation quarks is the charm (c) quark. It was predicated in 1970 and found shortly thereafter. The c quark has mass 1.3 GeV/c^2. The 3rd generation analogue to the u is the bottom (b) quark. The b quark was discovered in 1977 at Fermi lab and has a mass of 4.3 GeV/c^2. The top quark was found recently and has a mass of 175 GeV/c^2. The top quark is so massive, in fact, that no bound states involving it have been observed.

QuarkSymbolSpinCharge Baryon Number SCBTMass* UpU1/2+2/31/ MeV DownD1/2-1/31/ MeV CharmC1/2+2/31/ MeV StrangeS1/2-1/31/ MeV TopT1/2+2/31/ GeV BottomB1/2-1/31/30005 GeV

Protons and other types of hadrons interact via the strong nuclear force. Hadrons are further classified into mesons and baryons. Mesons have spin quantum numbers of either 0 or 1. Mesons also have masses that are between the mass of protons and the mass of electrons. The different types of mesons include pions, kaons or K mesons, and eta mesons. Protons and neutrons are the best known baryons, but there are many more types of baryons. They include the lamda, sigma, delta, xi, and omega baryons. Baryons have odd half integer spin quantum numbers (1/2, 3/2, 5/2, etc). They have masses greater than or equal to the mass of protons. Protons are very stable subatomic particles, but all other types of baryons decay. Neutrons decay after a mean lifetime measured in minutes, but the other types of baryons have lifetimes less than about a ten billionth of a second. When baryons decay, the final product always includes a proton. Hadrons are a type of subatomic particles that include the familiar protons and neutrons as well as many more exotic types of particles. The Large Hadron Collider (LHC) is so named because high energy particle physicists will use it to accelerate protons, which are a type of hadrons, to speeds very nearly the speed of light.

ParticleSymbol Anti- particle Makeup Rest mass MeV/c 2 SCBLifetimeDecay Modes Pionπ+π+ π-π- udud x10 -8 μ+νμμ+νμ Pionπ0π0 Self x γ KaonK+K+ K-K- usus x10 -8 μ + ν μ, π + π 0 KaonK0sK0s K0sK0s 1* x π + π -,2π 0 KaonK0LK0L K0LK0L 1* x10 -8 π+e-νeπ+e-νe Etaη0η0 Self2* < γ, 3μ Eta primeη 0' Self2* π+π-ηπ+π-η Rhoρ+ρ+ ρ-ρ- udud x π+π0π+π0 Rhoρ0ρ0 Self1.uu, dd x π+π-π+π- Omegaω0ω0 Selfuu, dd x π+π-π0π+π-π0 PhiφSelfs x K + K -,K 0 K 0 DD+D+ D-D- cdcd x K + _, e + _ DD0D0 D0D0 cucu x [K,μ,e] + _ DD+sD+s D-sD-s cscs x K + _ J/PsiJ/ψSelfc x e + e -, μ + μ -...

ParticleSymbolMakeup Rest mass MeV/c 2 SpinBS Lifetime (seconds> Decay Modes Protonpuud938.31/2+10Stable... Neutronnddu939.61/ pe - ν e LambdaΛ0Λ0 uds / x pπ -, nπ 0 SigmaΣ+Σ+ uus / x pπ 0, nπ + SigmaΣ0Σ0 uds /2+16x Λ0γΛ0γ SigmaΣ-Σ- dds / x nπ - DeltaΔ ++ uuu12323/ x pπ + DeltaΔ+Δ+ uud12323/ x pπ 0 DeltaΔ0Δ0 udd12323/ x nπ 0 DeltaΔ-Δ- ddd12323/ x nπ - Xi Cascade Ξ0Ξ0 uss13151/ x Λ0π0Λ0π0 Xi Cascade Ξ-Ξ- dss13211/ x Λ0π-Λ0π- OmegaΩ-Ω- sss16723/ x Ξ 0 π -, Λ 0 K - LambdaΛ+cΛ+c udc22811/2+102x

Bosons Bosons are force mediators and have integer spin (0,1, etc.). Because of this integer spin, they do not obey the Pauli Exclusion Principle. Bosons may be either massive like the W and Z bosons or massless like the photon or gluon. The Higgs boson is the last particle predicted by the Standard Model that has yet to have been found. The Higgs is predicted to be the reason everything in the universe has mass. It is also supposed to break the ElectroWeak symmetry: the fact that the EM boson is massless while the Weak bosons have mass.